Shelf



FIG. 1 is a top, front, right side perspective view of a shelf showing my new design;

FIG. 2 is a top, rear, left side perspective view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is an enlarged left side elevation view thereof;

FIG. 6 is an enlarged right side elevation view thereof;

FIG. 7 is a top plan view thereof;

FIG. 8 is a bottom plan view thereof; and,

FIG. 9 is a detailed view of the area in circle 9 in FIG. 2.

The broken lines in the drawings illustrate portions of the shelf that form no part of the claimed design. 

CLAIM The ornamental design for a shelf, as shown and described. 